Low-voltage transconductance amplifier/filters

Abstract

Wireless communications devices must handle a wide range of useful signal levels and must also cope with large interfering signals of nearby frequencies. They often use transconductance amplifiers / filters as building blocks as such amplifier / filters exhibit good characteristics of both amplification and filtering. The transconductance cells described make use of feedbacks which involve no signal conversions. As the result, the cells have high linearity and yet can operate at low voltage.

Description

The invention resides in the field of wireless communication devices and systems where a wide variety of signals need to be handled. In particular it relates to transconductance cells for amplifying / filtering wireless signals, which cells have a high linearity over a wide range of signal levels and yet require a low operational voltage.BACKGROUND OF INVENTIONIn typical applications, a wireless receiver must operate over a wide range of signal levels as well as large interfering signals. The interfering signals emanate from users in adjacent channels, as well as from transmission sources which may be relatively far removed in frequency but have a large transmission power. When two interfering signals at frequencies f1 and f2 (where f1 and f2 are close to the desired signal frequency) are present, they will produce--due to amplifier nonlinearity--intermodulation products at frequencies 2f2-f1 and 2f1-f2. These can fall at frequencies close to the desired signal frequency. The resultin...

AI Technical Summary

Problems solved by technology

The resulting interference causes measurable degradation of the bit error rate (BER) in digital communication systems.

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